Combination of synchronised assembly precedence matrices

Abstract The planning of assembly lines has always been a complex task, as a large number of factors that influence and disrupt production must be considered. Uncertainties in the early planning stages necessitate adjustments to the initial assumptions for the detailed assembly line plan throughout the planning project. Notably, the experience of assembly planners enables the integration of changing requirements into the planning process. This experience-based methodology is reaching its limits due to the increasing complexity of product variants and product portfolios. Newer data-driven approaches in assembly planning enable high productivity and the targeted use of synergies in assembly lines by utilising descriptive systematics that facilitate digital processing, thereby creating the basis for utilising digital planning assistance systems. For example, assembly precedence matrices (APMs) can structure and digitally represent the dependencies between assembly operations. If product variants with partially different assembly contents—whether in terms of the quantity of assembly operations or the specific activities within assembly operations—are processed within an assembly line, the individual consideration of these variants is no longer sufficient to optimise the system. To enable holistic optimisation, the synchronisation of APMs ensures consistency across variants. This is achieved through an expansion step, which integrates all relevant assembly operations into every APM within the product portfolio, followed by a transformation through row and column rearrangements. The synchronisation thus creates a daily basis for describing the assembly precedence relationships (APRs) of different product variants within the same product family. The scientific findings gained in this paper result from combining synchronised APMs of a mixed-model assembly line (MMAL) into a joint APM. The result includes defining operators for combining unified APM grids for a given product portfolio with different cell entries, taking into account application-related aspects. By combining the APMs of the product portfolio under consideration, APRs for the assembly procedure analysis can be described holistically as part of the assembly planning process. This enables analyses and optimisations for planning, such as assembly line balancing (ALB), the design of hybrid assembly structures, or the dimensioning of assembly system networks.